NumberResearchThousands-blocks in 423-278
This prefix’s ten 1,000-number blocks and who holds each — 10 on record · from the daily NANPA thousands-block report, 09/19/2026
The ten 1,000-number thousand-blocks inside prefix 423-278 and who was initially assigned each. Under pooling these blocks often belong to different carriers — the single prefix-level “assignee” is usually just the pool / code holder, not who holds the numbers. ← all 423 blocks
Most active assignees, all time — NPA 423
New assignments by month
Sep 2026
Aug 2026
Jul 2026
Jun 2026
May 2026
Apr 2026
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Jan 2026
Dec 2025
Nov 2025
Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2006-12-28 | 423-278-0XXX | 0000–0999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - TN | 6673 | GREENEVL | TN |
| — | 423-278-1XXX | 1000–1999 | Reserved | LEVEL 3 COMMUNICATIONS, LLC - TN | 4806 | GREENEVL | TN |
| 2008-04-08 | 423-278-2XXX | 2000–2999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - TN | 6673 | GREENEVL | TN |
| — | 423-278-3XXX | 3000–3999 | Reserved | LEVEL 3 COMMUNICATIONS, LLC - TN | 4806 | GREENEVL | TN |
| 2007-08-10 | 423-278-4XXX | 4000–4999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - TN | 6673 | GREENEVL | TN |
| 2007-02-26 | 423-278-5XXX | 5000–5999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - TN | 7278 | GREENEVL | TN |
| 2007-06-19 | 423-278-6XXX | 6000–6999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - TN | 6673 | GREENEVL | TN |
| 2025-07-29 | 423-278-7XXX | 7000–7999 | Assigned | CHARTER IP ENABLED SERVICES, LLC | 792K | GREENEVL | TN |
| 2003-12-01 | 423-278-8XXX | 8000–8999 | Assigned | NEW CINGULAR WIRELESS PCS, LLC - GA | 6214 | GREENEVL | TN |
| 2008-05-01 | 423-278-9XXX | 9000–9999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - TN | 4806 | GREENEVL | TN |
Source: NANPA Thousands Block Assignment Report (All Regions, Public), file date 09/19/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.